The present invention concerns a process to synthesize a catalyst performing Water-Gas shift reaction at a temperature more than 300° C. corresponding to a high temperature (HTS).
Commercial HTS catalysts are today mostly made of Fe and Cr oxide. Plant operating issues can result from catalyst deactivation if the plant is operated at low steam loadings, due to the reduction of Fe oxide to metallic Fe that catalyze in these conditions the hydrocarbon and coke formation. Moreover the use of Cr is today in contradiction with safe plant operation, as Cr (VI) is harmful for grounds, plants, animals and humans.
The water gas shift (WGS) reaction plays a key role in Steam Reforming (SR) plants, increasing the H2 production and reducing the CO content in the exit stream. The WGS reaction is most of the time performed in two successive steps: High Temperature Water-Gas Shift (HTS) and Low-Temperature Water Gas Shift (LTS). The high temperature step is generally performed on Iron and Chromium oxides based catalysts, at temperatures higher than 350° C., while the second step is performed at lower temperature (200° C.) using Cu-based catalysts.
Main advantages to use HTS technology are:                Lowest production of by-products, like low molecular weight alcohols, that are favored by decreasing temperature and increasing Cu-content        Lowest production of steam, strong advantage when steam is not or not well valorized by the plant        Able to accept higher content of CO, resultant exothermic effect is not an issue because the catalyst is more robust against sintering        Most robust against poisoning        
The catalyst present in the first reactor is sensitive to operating conditions. Low steam content in process gas can irreversibly damage Fe-based catalysts, by formation of iron carbides or metallic iron, hence changing the selectivity of the catalyst and increasing hydrocarbon content in the product gas. In addition, Chromium-containing catalysts are harmful for health and environment and their production and use are today subjected to stringent regulations.
Removing chromium from HTS catalysts has already been attempted. However, such catalysts are still submitted to reduction of Iron oxide, hence being likely deactivated at low water content in process gas.
So, a problem is to provide an improved catalyst.